It is known that microorganisms produce a variety of antitumor antibiotics. For example, it has been reported that pluramycin (J. Antibiotics 9A, 75, 1956), neopluramycin (J. Antibiotics 23, 354, 1970), kidamycin (J. Antibiotics 24, 599, 1971) and hedamycin (Helv. Chim. Acta 60, 896, 1977) are all elaborated by microorganisms. However, there is a constant demand for new and better substances having antitumor activity of value-for use as medicines.
To meet the above-mentioned demand, the inventors of this invention made a diligent exploration for substances having antitumor activity and discovered in culture broths of a certain microorganism of the genus Streptomyces a substance having a cytotoxic effect on mouse leukemia cells (P-388) as well as other antitumor and antimicrobial activities. The substance was isolated its physicochemical and biological properties were determined, thus this invention was accomplished.